Optic disc melanocytoma: Predicting visual field defects and recognizing malignant transformation - a review of...

Optic disc melanocytoma (ODM) is a benign pigmented tumor historically regarded as stationary. ODM can produce visual dysfunction and rarely undergoes malignant transformation. We synthesize evidence on predicting visual field defects and recognizing malignant transformation. Optical coherence tomography angiography (OCTA) studies demonstrate that visual field defects correlate more strongly with absent intratumoral blood vessel networks than with tumor size. A validated threshold of capillary density loss > 0.75% per year identifies patients at increased risk of visual field progression. OCTA measurements demonstrate high intra-device reproducibility (intraclass correlation coefficients >0.8) but poor inter-device reliability, requiring strict standardization. Regarding malignant transformation, a synthesis of case series indicates a rate of approximately 1.7%, with transformation potentially occurring decades after diagnosis. OCTA detects malignant transformation through identification of intrinsic tumor vasculature. In choroidal studies, intralesional vessel diameter ≥ 76.3μm has demonstrated 100% sensitivity and specificity for distinguishing melanoma from nevus; however, ODM-specific validation is needed. Key warning signs include progressive tumor growth, unexplained vision loss, vitreous seeding, and intrinsic tumor vasculature. Evidence-based surveillance protocols recommend imaging every 3-6 months for the first 2 years after detection of high-risk features, then annually if stable. These findings support long-term surveillance with multimodal imaging and standardized quantification protocols.